Materials with increased magnetic anisotropies are desirable for various applications such as, for example, applications in the data storage industry where there is a continuous need to increase storage densities. Data storage media that can hold densities approaching 1 Tbit/in2 will require materials with magnetic anisotropies greater than conventional media materials. There are known bulk permanent magnetic materials having crystalline phases with magnetocrystalline anisotropy that theoretically can hold densities greater than 1 Tbit/in2. For bulk permanent magnetic materials, special heat treatments are typically used to control the phase formation and microstructure to optimize the material properties. In order to incorporate these materials into a data storage media, the correct crystalline phase must be obtained within a microstructure of fine, nanocrystalline, exchange decoupled or partially exchange decoupled grains while maintaining thermal stability.
L10 phase FePt binary alloys have magnetocrystalline anisotropy as high as 7×107 erg/cc, which is well suitable for future magnetic recording media to achieve density over 1 Tb/in2. However, FePt is typically deposited as the face centered cubic (fcc) phase (i.e., the A1 phase) and subsequent annealing is needed to transform (i.e., chemically order) the material into the high anisotropy L10 phase.
This high temperature processing is likely to enhance grain growth, which is opposite to the small grain size requirement for high density recording. On the other hand, fully ordered FePt media generally have a coercivity over 4 Tesla, which is beyond current writer technology capabilities. It would be desirable to produce FePt media with a small grain size and with magnetic characteristics that are compatible with current writer technology.